US72/73
Single Coil Fan Driver
3901090261
Page 3 of 9
Data Sheet
Rev. 002
May/04
1. Glossary of Terms
Full Bridge: Two output drivers that can both source or sink current. When a load is placed between the
drivers, current can flow through the load in both directions.
FG: The Frequency Generator or tachometer signal; provides one pulse for every magnetic pole
RD: The Rotation detection or Lock Alarm signal is high when the rotor is blocked or spinning very slowly.
MilliTesla (mT), Gauss: Units of magnetic flux density; 1 milliTesla = 10 Gauss
Single Coil Fan: a fan with only one coil winding, usually requiring a bipolar or full-bridge driver
Locked rotor: The condition of a fan that has stopped spinning due to mechanical blockage
2. Absolute Maximum Ratings
Supply Voltage, VDD (overvoltage)
28V
Output Voltage, FG or RD
28V
Output Current, IOUT
500mA
Operating Temperature Range, TA
-40 to 85
°C
Junction Temperature, Tj
125
°C
Storage Temperature, Ts
-55 to 150
°C
ESD Sensitivity (AEC Q100 002)
2KV
Magnetic Flux Density
No limit
Exceeding the absolute maximum ratings may cause permanent damage. Exposure to absolute-
maximum-rated conditions for extended periods may affect device reliability.
3. US72/73 Electrical Specifications
DC Operating Parameters TA = 25
oC, V
DD = 12V (unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Units
Supply Voltage
VDD
Operating
4.5
28
Volts
Supply Current
IDD
VDD = 24V, No Load
4
6
mA
On Resistance
Rdson
Full bridge, Rnmos + Rpmos
3
5.3
Ohms
Bridge Current
Iload
Peak
500
mA
Bridge Current
Iload
Continuous
350
mA
Thermal Resistance
Rth
one-sided PCB, zero LFPM
150
o
C/Watt
Locked-Rotor Period
ton
0.25
S
Locked-Rotor period
toff
1.25
S
Freewheel Switching delay
tfw
200
uS
FG/RD Output Leakage
Ioff
Vout = 24V
10
uA
FG/RD On voltage
Vdson
Iout = 5mA
0.5
Volts
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